#include<bits/stdc++.h>
using namespace std;

double pi = acos(-1.0);
double eps = 1e-9;
void solve() {
    int n, k;
    cin >> n >> k;

    vector<pair<double, pair<int, int>>> a(n);
    for(int i = 0; i < n; i++){
        cin >> a[i].second.first >> a[i].second.second;
        a[i].first = atan2(a[i].second.second, a[i].second.first);
    }
    if(abs(a[0].first - a.back().first) < eps) {
        cout << fixed << setprecision(10) << 2 * pi << '\n';
        return;
    }

    sort(a.begin(), a.end());

    double mx = 0.0;
    for(int i = 0; i < n; i++) {
        int j = (i + k) % n;

        double x = a[j].first - a[i].first;
        if(x <= eps){
            x += 2 * pi;
        }
        mx = max(mx, x);
    }
    cout << fixed << setprecision(10) << mx << '\n';
}

int main() {
    ios::sync_with_stdio(0); cin.tie(nullptr);
    int t = 1;
    cin >> t;
    while(t--) {
        solve();
    }
}